The biggest desert in the world is in Africa, and is called the Sahara. It is almost as large as the Atlantic Ocean, but instead of water it is all sands and rocks. Like the ocean, it is visited with storms; dreadful gales, when the wind scoops up thousands of tons of sand and drives them forward, burying and crushing all they meet. And it has islands, too--small green patches, where springs bubble through the ground, and ferns and acacias and palm-trees grow. When a traveler sees one of these fertile spots afar off, he feels as a tempest-tossed sailor does at sight of land. It is delightful to quit the hot, baking sun, sit in shadow under the trees, and rest the eyes, long wearied with dazzling sands, on the sweet green and the clear spring. Oases, these islands are called. Long distances divide them. It is often a race for life to get across from one to the other. Sometimes people do not get across! In 1805, a caravan of 2,000 persons died miserably of heat and thirst in the great desert, and the sand covered them up. Do you wonder at my saying that the desert eats men? Now, you will be puzzled to guess what sort of ship it is which swims this dry ocean. It is the camel--an animal made by God to endure these dreadful regions, in which no other beast of burden can live and travel. I dare say many of you have seen camels in menageries. They are ugly animals, but very strong, swift and untiring. With a load of 800 pounds on his back, a camel will travel for days at the rate of eight miles an hour, which is as fast as an ordinary ship can sail. More wonderful still, he will do this without stopping for food or water. Nature has provided him with an extra stomach, in which he keeps a store of drink, and with a hump on his back, made of jelly-like fat, which, in time of need, is absorbed into the system and appropriated as food. Is it not strange to think of a creature with a cistern and a meat-safe inside him? A horse would be useless in the desert, where no oats or grass can be had; but the brave, patient camel goes steadily on without complaint till the oasis is reached: then he champs his thorn bushes, fills himself from the spring, allows the heavy pack to be fastened on his back again, and is ready for further travel.